The U.S. Census Bureau treats the Commonwealth of Puerto Rico as the statistical equivalent of a state for data presentation purposes. Each state and statistically equivalent entity is assigned a two-digit Federal Information Processing Standards (FIPS) code in alphabetical order by state name, followed in alphabetical order by Puerto Rico and the Island Areas. Each state and statistically equivalent entity also is assigned the two-letter FIPS/U.S. Postal Service code.

The U.S. Census Bureau recognizes barrios and barrios-pueblo as the primary legal divisions of municipios. These entities are similar to the minor civil divisions (MCDs) used for reporting decennial census data in 28 states of the United States. Subbarrios in 23 municipios are the primary legal subdivisions of the barrios-pueblo and some barrios. The U.S. Census Bureau presents the same types of Census 2000 data for these " sub-MCDs" as it does for the barrios and barriospueblo. (There is no geographic entity in the United States equivalent to the subbarrio.) Each barrio, barrio-pueblo, and subbarrio is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.

There are no incorporated places in Puerto Rico; instead, the U.S. Census Bureau provides decennial census data for two types of census designated places (CDPs): (1) zonas urbanas, representing the governmental center of each municipio, and (2) comunidades, representing other settlements. For Census 2000, there are no minimum population size requirements for CDPs. (For the 1990 census, the U.S. Census Bureau had required comunidades to have at least 1,000 people.)

Each zona urbana and comunidad is assigned a five-digit Federal Information Processing Standards (FIPS) code in alphabetical order within Puerto Rico.
Some types of geographic entities do not apply in Puerto Rico. For instance, Puerto Rico is not in any census region or census division. In addition, the U.S. Census Bureau does not tabulate data for state legislative districts and traffic analysis zones in Puerto Rico. (See also CONGRESSIONAL DISTRICT (CD).)

The data on year of entry were derived from answers to Question 9.
All respondents born outside the United States were asked for the year in which they came to live in the United States. This includes people born in Puerto Rico and U.S. Island Areas; people born abroad of an U.S. citizen parent or parents; and the foreign born. (See "Citizenship Status.") For the Puerto Rico Community Survey, respondents were asked for the year in which they came to live in Puerto Rico.

Respondents were directed to indicate the year they entered the U.S. (or Puerto Rico, for the Puerto Community Survey) "to live." For respondents who have entered the U.S. (or Puerto Rico for the Puerto Rico Community Survey) multiple times, the interviewers were instructed to request the most recent year of entry. For respondents who either did not ask the interviewer for clarification or for those who mailed back the questionnaire without being interviewed in person, it was difficult to ensure that respondents interpreted the question as intended.
Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations may have year of entry distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the year of entry distribution. This is particularly true for areas with a substantial GQ population.

The data on citizenship status were derived from answers to Question 8. The responses to this question were used to determine the U.S. citizen and non-U.S. citizen populations as well as to determine the native and foreign-born populations. Respondents were asked to select one of five categories:
(1) born in the United States,
(2) born in Puerto Rico, Guam, the U.S. Virgin Islands, or Northern Marianas,
(3) born abroad of U.S. citizen parent or parents,
(4) U.S. citizen by naturalization, or
(5) not a U.S citizen. Respondents indicating they are a U.S. citizen by naturalization are also asked to print their year of naturalization. People born in American Samoa, although not explicitly listed, are included in the second response category.

For the Puerto Rico Community Survey, respondents were asked to select one of five categories:
(1) born in Puerto Rico,
(2) born in a U.S. state, District of Columbia, Guam, the U.S. Virgin Islands, or Northern Marianas,
(3) born abroad of U.S. citizen parent or parents,
(4) U.S. citizen by naturalization, or
(5) not a U.S. citizen. Respondents indicating they are a U.S. citizen by naturalization are also asked to print their year of naturalization. People born in American Samoa, although not explicitly listed, are included in the second response category.

When no information on citizenship status was reported for a person, information for other household members, if available, was used to assign a citizenship status to the respondent. All cases of nonresponse that were not assigned a citizenship status based on information from other household members were allocated the citizenship status of another person with similar characteristics who provided complete information. In cases of conflicting responses, place of birth information is used to edit citizenship status. For example, if a respondent states he or she was born in Puerto Rico but was not a U.S. citizen, the edits use the response to the place of birth question to change the respondent's status to "U.S. citizen at birth."

Respondents who indicated that they were born in the United States, Puerto Rico, a U.S. Island Area (such as Guam), or abroad of American (U.S. citizen) parent or parents are considered U.S. citizens at birth. Foreign-born people who indicated that they were U.S. citizens through naturalization also are considered U.S. citizens.

The native population includes anyone who was a U.S. citizen or a U.S. national at birth. This includes respondents who indicated they were born in the United States, Puerto Rico, a U.S. Island Area (such as Guam), or abroad of American (U.S. citizen) parent or parents.

The foreign-born population includes anyone who was not a U.S. citizen or a U.S. national at birth. This includes respondents who indicated they were a U.S. citizen by naturalization or not a U.S. citizen. The American Community Survey questionnaires do not ask about immigration status. The population surveyed includes all people who indicated that the United States was their usual place of residence on the survey date. The foreign-born population includes naturalized U.S. citizens, Lawful Permanent Residents (immigrants), temporary migrants (e.g., foreign students), humanitarian migrants (e.g., refugees), and unauthorized migrants (people illegally present in the United States).

Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations may have citizenship status distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the citizenship status distribution. This is particularly true for areas with a substantial GQ population.

In the 1996-1998 American Community Survey, the third response category was "Yes, born abroad of American parent(s)." However, since 1999 in the American Community Surveys and since the 2005 Puerto Rico Community Surveys, the response category was "Yes, born abroad of American parent or parents."